Sand casting mold

ABSTRACT

An improved sand casting mold having a pair of separable mold elements is provided with a casting chamber which is offset from a main parting plane along which the mold elements are joined with the mold elements providing mating beveled surfaces between the main parting plane and the casting chamber to define an auxiliary angular parting line therebetween so that any incidental flashing on a casting formed within the casting chamber occurs along the parting line in such a portion on the casting so as to be readily removed by automatic surface grinding machines. The beveled surfaces of the mold elements along the angular parting line further serve to strengthen the corners of the mating mold elements so as to resist breakage during handling and use of the mold.

United States Patent [191 Nieman 1 Aug. 5, 1975 [73] Assignee:Caterpillar Tractor Co., Peoria,

22 Filed: Aug.27,1973

211 App]. No.1 391,992

[52] US. Cl. 164/364; 164/360; 164/363 [51] Int. Cl. B22C 9/02 [58]Field of Search 164/358, 359, 360, 362,

803,182 3/1951 Germany 249/109 520,679 6/1953 Belgium 249/1 10 623,3501959 Italy 249/110 Primary E.\'aminerRoy Lake Assistant E.\aminerPaul A.Bell Attorney, Agent, or Firm-Ralph E. Walters [5 7 ABSTRACT An improvedsand casting mold having a pair of separable mold elements is providedwith a casting chamber which is offset from a main parting plane alongwhich the mold elements are joined with the mold elements providingmating beveled surfaces between the main parting plane and the castingchamber to define an auxiliary angular parting line therebetween, sothat any incidental flashing on a casting formed within the castingchamber occurs along the parting line in such a portion on the castingso as to be readily removed by automatic surface grinding machines. Thebeveled surfaces of the mold elements along the angular parting linefurther serve to strengthen the corners of the mating mold elements soas to resist breakage during handling and use of the mold.

6 Claims, 3 Drawing Figures BACKGROUND OF THE INVENTION DESCRIPTION OFTHE PREFERRED EMBODIMENTS Referring more particularly to the drawing, anim- In the manufacture of metal castings, superfluous Proved Castingmold embodying the Principles of the metal is often formed about theperiphery of the casting coincident to where the parting lineof thecasting mold intersects the casting cavity. One common cause of suchsuperfluous metal is the flashing of metal along the parting line due toimperfectly mating parting surfaces on the opposite elements of themold. Another cause is the breakage of the outside corners formed by theintersection of such parting surfaces with the casting cavity.

Heretofore, the parting surfaces of prior molds have been orientedsubstantially perpendicular to the casting cavity creating right angularoutside corners. Such right angular corners are highly susceptible tobreakage during handling and use of the mold due to the frangible natureof the sand casting material used to construct such casting molds.

Because such superfluous metal is disposed about the periphery of thecasting, the most frequently used method to remove such metal is by ahand controlled grinding wheel. Hand grinding is an extremely laboriousand time-consuming operation which greatly contributes to the overallexpense of the casting.

Another problem associated with the broken corners is that if the loosematerial therefrom is in the casting cavity when the molten metal ispoured, such material becomes lodged in the casting resulting inundesirable imperfections therein.

OBJECTS OF THE INVENTION Accordingly, it is an object of this inventionto provide an improved sand casting mold for producing metal castings.

Another object of this invention is to provide such sand casting moldwherein the marginal edge of the casting chamber along the parting lineof the mold is formed at an obtuse angle for greater resistance tobreakage during handling and use of the mold.

Another object of this invention is to provide a sand casting moldwherein any incidental flashing occurring along the parting surfacesconnected with the casting chamber is angled outwardly from the surfaceof a single side of the casting chamber to facilitate the removal ofsuch flashing from a casting manufactured in such a mold.

Other objects and advantages of the present invention will become morereadily apparent upon reference to the accompanying drawing andfollowing description.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a longitudinalcross-sectional view of an improved casting mold embodying theprinciples of the present invention.

FIG. 2 is a fragmentary sectional view of a corner of the castingchamber shown in FIG. 1, but illustrating an alternate embodiment of thepresent invention.

FIG. 3 is afragmentary sectional view of a corner of a casting producedby the alternate embodiment of the casting mold of FIG. 2.

present invention is generally indicated at 10 and is constructed from amolding sand or other suitable material. As best shown in FIG. 1, atwo-part flask 12 including an upper flask portion 14 and a lower flaskportion 16 is utilized to support the mold. The upper flask portion 14is provided with a lower end 18 which is separably joined in abuttingrelation to an upper end 20 of the lower flask portion 16 along agenerally horizontal main parting plane 22 formed therebetween.

An upper cope element 24 of the mold 10 is formed in the upper flaskportion 14. The upper cope element 24 is provided with a lower partingsurface 26 disposed generally along the main parting plane 22. The uppercope element also includes a protuberance 28 having a substantially flatouter surface 30 disposed in spaced substantially parallel relation tothe main parting plane 22. The protuberance has a continuous marginallyextending beveled side surface 32 which extends between the lowerparting surface of the upper cope element and the flat outer surface ofthe protuberance. The intersection of the beveled side surface 32 andthe flat outer surface 30 of the protuberance defines a continuousmarginally extending corner 33 having an included angle greater thandegrees.

A lower drag element 34 of the mold 10 is formed in the lower flask 16.The lower drag element is provided with an upper parting surface 36disposed for mating engagement with the lower parting surface 26 of theupper cope element 24 along the main parting plane 22. The lower dragelement also includes a cavity 38 formed in its upper parting surfacewhich is defined by a recessed bottom wall 42 and a continuousmarginally extending sidewall 44. The sidewall is divided into a beveledouter portion 46 extending inwardly from the upper parting surface 36and an inner sidewall portion 48 extending outwardly from the bottomwall 42. The beveled outer portion 46 is disposed in substantiallyparallel relation to the beveled side surface 32 of the protuberance sothat cooperative mating engagement therewith defines an auxiliaryangular parting line 49 therebetween. The inner sidewall portion 48 isdisposed generally normal to the bottom wall 42 and intersects with thebeveled outer portion 46 intermediate the upper parting surface 36 andthe bottom wall to form a continuous marginally extending corner 50therebetween. The continuous marginally extending corner 50 is providedwith an included angle greater than 90 degrees which is substantiallyequal to the corner 33 of the protuberance 28 on the upper cope element24.

Insertion of the protuberance 28 into the cavity 38 is effective to forma substantially closed casting chamber 52 in the mold 10 having aremovable wall defined by the flat outer surface 30 of the protuberanceand stationary walls defined by the inner sidewall portion 48 and therecessed bottom wall 42 of the cavity. The protuberance and cavity areconstructed so that their respective continuous marginally extendingcorners 33 and 50 are disposed in closely adjacent relationship todefine a substantially right angular inner corner 54 of the castingchamber 52. Thereby, the auxiliary angular parting line 49 interconnectsthe main parting plane 22 with the casting chamber 52 along such innercorner.

The casting mold also includes a gating system, generally indicated at56, for communicating molten metal, not shown, into the casting chamber52. such a gating system includes a vertically disposed downsprue 57, ahorizontal runner 58, a riser cavity 59, and an ingate 60. It should benoted that the present invention is not intended to be limited by theabove enumerated components of the gating system which are used merelyfor illustrative purposes, as numerous other components and combinationsthereof will be readily apparent to those skilled in the art.

Operation While the operation of the present invention is believed to beclearly apparent from the foregoing description, further amplificationwill subsequently be made in the following brief summary of suchoperation.

In operation, after assembly of the mold 10, a predetermined quantity ofmolten metal is introduced into the casting chamber 52 for themanufacture of a casting which will acquire a shape conforming to thatof the casting chamber 52. Such molten metal is introduced into the moldin the usual manner through the gating system 56, wherein molten metalwhich is poured into the downsprue 57 is directed through the runner 58into the riser cavity 59. The molten metal is then channelled from theriser cavity into the casting chamber through the ingate 60.

Ordinarily, any mislocation of the upper cope element 24 on the lowerdrag element 34 of the mold 10 would cause their respective partingsurfaces 26 and 36 to be imperfectly mated during assembly. Accordingly,when the casting is poured imperfect mating of the parting surfacesintersecting the casting chamber 52 would allow the flashing of moltenmetal from the chamber along the auxiliary parting line 49. Thistendency is substantially minimized with the mold of the presentinvention, however, because of the piloting function of the beveledprotuberance 28 into the beveled outer portion 46 of the cavity 38 whichvirtually insures proper assembly of the mold. If there should be someimperfection in or damage to the mating mold surfaces some flashing mayoccur about the periphery of the casting produced. Even when thisoccurs, the structure of the present invention facilitates the moreeconomical removal of such flash material by the utilization of theauxiliary angular parting line 49 which is oriented outwardly from asingle side defined by the outer surface 30 of the protuberance of thecasting produced in such a mold. Consequently, this permits the flashmaterial to be removed in a single pass over the flashing side of thecasting with a belt type grinder.

The corner breakage problem associated with the right or acute angularoutside corners formed in prior molds by the intersection of partingsurfaces with casting chambers thereof is also alleviated by theparticular orientation of the auxiliary parting line 49 of the presentinvention. The angular disposition of the beveled side surface 32 of theprotuberance and the beveled outer portion 46 of the cavity forming theauxiliary parting line provide the outside corners of the present molddefined by the continuous marginally extending corners 33 and 50,respectively, with relatively large, 6

the casting chamber, the corners 33 and are provided with the greatestequalized obtuse angles possible so as to have greater strength in orderto resist breakage during handling and use of the mold.

Second Form An alternate embodiment of the present invention isillustrated in FIG. 2, wherein components identical to those employed inthe first form are designated by corresponding reference numerals. Inthe second embodiment, the protuberance 28 is formed somewhat smallerthan the cavity 38 so that the continuous marginally extending beveledside surface 32 is spaced a predetermined parallel distance apart fromits formerly engaging beveled outer portion 46 of the cavity for forminga fin cavity 62 therebetween. As partially illustrated in FIG. 3, acasting 64 is formed in the alternate mold of FIG. 2 having a fin 66conforming to the fin cavity 62. The fin projects outwardly from thesurface of the casting formed by the outer surface 30 of theprotuberance at an oblique angle along the corner thereof formed by thesubstantially right angular inner corner 54 of the casting chamber 52.

Operation of the Second Form The structure of the alternate casting moldillustrated in FIG. 2 operates in essentially the same manner as thestructure heretofore described, wherein molten metal is introduced intothe casting chamber 52 for the manufacture of the casting 64 shown inFIG. 3. As is well known in the art, relatively thin flash materialsolidifies very rapidly which may have an adverse chilling affect on thecasting adjacent such flashing. Such chilling may be undesirable inparticular instances because it increases the hardness of the metalwhich makes machining of the casting more difficult. The particularconstruction of the alternate casting mold of FIG. 2 prevents suchchilling by eliminating the presence of such relatively thin flashmaterial about the periphery of the casting. This is accomplished by thepurposeful spacing of the beveled side surface 32 of the protuberancefrom the beveled outer portion 46 of the cavity so that the relativelythick fin 66 is produced in the fin cavity 62 about the casting 64. Thefin cavity is adapted to contain a sufficient mass of molten metal forthe particular casting being produced so that the solidification of thefin 66 formed therein is sufficiently retarded so as not to induce achilling affect on the body of the casting. The fin is latereconomically removed from the casting by the belt grinding operationpreviously described.

While the invention has been described and shown with particularreference to the preferred embodiment, it will be apparent thatvariations might be possible that would fall within the scope of thepresent invention which is not intended to be limited except as definedin the following claims.

What is claimed is:

I. An improved sand casting mold comprising; a pair of mold elementsseparable along a main parting plane formed therebetween;

means forming a substantially closed casting chamber in such castingmold with the entire casting chamber being disposed in spaced offsettingrelation to said main parting plane; and

auxiliary parting line means extending in interconnecting relationbetween said main parting plane and said casting chamber.

2. An improved sand casting mold comprising;

a pair of mold elements having engaging planar surfaces defining a mainparting plane along which such mold elements are separable;

means forming a relatively large cavity within one of said mold elementsextending inwardly from its respective engaging surface; and

means forming a protuberance on the other of said mold elementsextending outwardly from its respective engaging surfaces, saidprotuberance being adapted for receipt into said cavity of said one ofsaid mold elements in nonfilling relation therewith to define asubstantially closed casting chamber in said mold, which casting chamberis disposed entirely in spaced offsetting relation to said main partingplane of the mold.

3. The casting mold of claim 2 wherein;

said protuberance includes an outer surface defining a removable wall ofsaid casting chamber and a continuous marginally extending beveled sidesurface adapted to be readily receivable within said cavity; and

said cavity includes a continuous marginally extending inner side wallhaving a portion defining a stationary wall of said casting chamber andan adjoining beveled outer portion defining the portion of said cavitywhich is adapted to receive said protuberance, said beveled outerportion being disposed in substantially parallel relation to saidbeveled side surface of the protuberance when assembled so as tocooperatively define therewith an auxiliary parting line interconnectingsaid main parting plane with said casting chamber so that any flashmaterial flowing therethrough during the casting operation may besubsequently expeditiously removable from a casting formed in the mold.

4. The casting mold of claim 3 including;

a continuous marginally extending corner defined by the intersection ofsaid beveled side surface of the protuberance with its outer surface;and

a continuous marginally extending corner disposed between said portionsof the inner sidewall forming said cavity with each of said continuousmarginally extending comers forming a relatively blunt obtuse angle foradded strength in order to resist breakage during handling and use ofthe mold.

5. The casting mold of claim 4 wherein said outer surface of saidprotuberance and said stationary wall of the cavity form a substantiallyright angular inner corner of said casting chamber, and said auxiliaryparting line being inclined in substantially bisecting relation to saidinner corner so that said obtuse angles of the continuous marginallyextending corners of the casting mold are substantially equallymaximized.

6. The casting mold of claim 5 wherein said beveled side surface of saidprotuberance and said beveled outer portion of said inner sidewall ofthe cavity are spaced a predetermined distance apart to define a fincavity therebetween of a size to contain sufficient casting materialduring the casting operation to minimize premature chilling of suchmaterial in said inner corner of the casting chamber duringsolidification.

1. An improved sand casting mold comprising; a pair of mold elements separable along a main parting plane formed therebetween; means forming a substantially closed casting chamber in such casting mold with the entire casting chamber being disposed in spaced offsetting relation to said main parting plane; and auxiliary parting line means extending in interconnecting relation between said main parting plane and said casting chamber.
 2. An improved sand casting mold comprising; a pair of mold elements having engaging planar surfaces defining a main parting plane along which such mold elements are separable; means forming a relatively large cavity within one of said mold elements extending inwardly from its respective engaging surface; and means forming a protuberance on the other of said mold elements extending outwardly from its respective engaging surfaces, said protuberance being adapted for receipt into said cavity of said one of said mold elements in nonfilling relation therewith to define a substantially closed casting chamber in said mold, which casting chamber is disposed entirely in spaced offsetting relation to said main parting plane of the mold.
 3. The casting mold of claim 2 wherein; said protuberance includes an outer surface defining a removable wall of said casting chamber and a continuous marginally extending beveled side surface adapted to be readily receivable within said cavity; and said cavity includes a continuous marginally extending inner side wall having a portion defining a stationary wall of said casting chamber and an adjoining beveled outer portion defining the portion of said cavity which is adapted to receive said protuberance, said beveled outer portion being disposed in substantially parallel relation to said beveled side surface of the protuberance when assembled so as to cooperatively define therewith an auxiliary parting line interconnecting said main parting plane with said casting chamber so that any flash mateRial flowing therethrough during the casting operation may be subsequently expeditiously removable from a casting formed in the mold.
 4. The casting mold of claim 3 including; a continuous marginally extending corner defined by the intersection of said beveled side surface of the protuberance with its outer surface; and a continuous marginally extending corner disposed between said portions of the inner sidewall forming said cavity with each of said continuous marginally extending corners forming a relatively blunt obtuse angle for added strength in order to resist breakage during handling and use of the mold.
 5. The casting mold of claim 4 wherein said outer surface of said protuberance and said stationary wall of the cavity form a substantially right angular inner corner of said casting chamber, and said auxiliary parting line being inclined in substantially bisecting relation to said inner corner so that said obtuse angles of the continuous marginally extending corners of the casting mold are substantially equally maximized.
 6. The casting mold of claim 5 wherein said beveled side surface of said protuberance and said beveled outer portion of said inner sidewall of the cavity are spaced a predetermined distance apart to define a fin cavity therebetween of a size to contain sufficient casting material during the casting operation to minimize premature chilling of such material in said inner corner of the casting chamber during solidification. 